Circular slide rule

ABSTRACT

A circular slide rule comprises a central shaft having one or more information-bearing reference discs mounted thereon. A pair of overlapped cursor arms are mounted rotatably on the shaft in frictional engagement with each other, concentrically with the discs and overlying the outer face of one of them. The degree of frictional contact between the cursor arms is predetermined to cause the arms to rotate in unison about the shaft when a displacing force is applied to one arm only, but to permit the arms to rotate relative to each other when a restraining force is applied to one while a displacing force is applied to the other. In addition, the discs are arranged for free rotation relative to each other and provided with windows arranged to permit inspection of selected areas of underlying discs.

United States Patent Adams 1 Mar. 7, 1972 [54] CIRCULAR SLIDE RULE Primary ExaminerStephen J. Tomsky [72] inventor: Robert P. Adams, Albany, Oreg. Attorney-Eugene Farley [73] Assignee: Albany Enterprises, Inc., Albany, Oreg. ABSTRACT [22] 1 Filed: Apr. 7, 1970 A circular slide rule comprises a central shaft having one or more information-bearing reference discs mounted thereon. A [21] Appl' 26323 pair of overlapped cursor arms are mounted rotatably on the shaft in frictional engagement with each other, concentrically 52 us. Cl ..235/83, 235/120 with the discs d overlying the face of one them The [51] Int. Cl I v 27/00 degree of frictional contact between the cursor arms is [58] Field of Search ..235/83, 120 78, l 16 predetermined the arms in shaft when a displacing force is applied to one arm only, but to [56] References Cited permit the arms to rotate relative to each other when a restraining force is applied to one while a displacing force is UNITED STATES PATENTS applied to the other. In addition, the discs are arranged for free rotation relative to each other and provided with windows 2,996,246 8/1961 Swanson ..235/83 arranged to permit inspection of selected areas of underlying 2,477,556 7/1949 Shaw ..235/83 discs. 2,268,886 1/1942 McNamara ..235/83 3 Claims, 4 Drawing Figures l8 I2 50 I6 Patented March 7, 1972 3,648,025

zzmy so ROBERT p. ADAMS 34 )W 35 BY *7 "9 20 I8 24 30 22 F 4 ATTY.

CIRCULAR SLIDE RULE This invention relates to circular slide rules.

Although many types of circular slide rules heretofore have been devised, there has been a need for such a rule which is particularly applicable for use by scientists, engineers and educators who frequently are under the necessity of converting atomic percent and mole fraction to weight percent, or vice versa, and in addition need to have available for ready reference a catalog of the physical and chemical'properties of theelements.

It is the general purpose of the present invention to provide sucha circular rule which, in addition, may be applied to the interconversion of such physical constants as fahrenheit and centigrade temperatures, and to the solution of problems in multiplication, division and proportion.

It is a further purpose of the invention to provide a circular slide rule which inherently is very accurate, which has little or no parallax which is not complicated, which does not require the memorization of complex procedures for its use and which may be constructed as a precision instrument having a long and trouble-free service life.

The manner in which the foregoing and other objects of this invention are accomplished will be apparent from the accompanying specification and claims considered together with the drawings, wherein-:

FIGS. 1 and 2 are front and back plan views of the circular slide rule of the invention, respectively,

FIG. 2 being partly broken away to reveal concealed construction;

FIG. 3 is an exploded perspective view of the slide rule; and

FIG. 4 is a detail, sectional view taken along line 4-4 of FIG. 1.

The elements of the slide rule are mounted on a central shaft comprising a specially designed nut and bolt. The nut, indicated generally at includes a broad, flat head 12 of sufficient width to overlie the slide rule discs and having a hexagonal perimeter to accommodate a wrench. The inside face of the head is formed with an annular raised portion 14 which functions as a washer.

Extending inwardly from head 12 is a central, internally threaded boss divided into two segments: an inner segment of enlarged diameter 16 and an outer segment 18 of smaller diameter. The overall length of the central boss is predetermined and correlated with the dimensions of the associated bolt so that the bolt head bottoms against the end of the boss when bolt and nut are interengaged, thereby forming a clamp.

The associated bolt, indicated generally at 20, also has a broad, flat head 22 of hexagonal contour adapted for engagement by a wrench, and a lateral dimension sufficient to overlie the disc elements of the rule.

A post 24 extends outwardly centrally of the head. It has an enlarged threaded outer portion 26 which interengages the threaded boss of nut I0. A recess thus is formed between head 22 and threaded section 26. This mounts a circular, centrally perforated spring washer 28 which then may be clamped in position by the thrust exerted by the central boss of nut 10 when the latter is engaged with the bolt.

Boss segments 16 and 18 of the nut 10 thus form a stepped shaft which is used to mount the indicating and reference ele ments of the slide rule assembly.

To make possible the use of these elements in their intended manner, there is journaled on the reduced section 18 of the shaft a freely rotatable sleeve 30. This has an external diameter which preferably is substantially equal to that of shaft section 16. However, its length is somewhat shorter than the length of reduced shaft section 18. This leaves between the sleeve and shaft section 17 a space which is used to mount a first reference disc 32.

Disc 32 preferably is fabricated from a stiff, durable sheet material such as metallic aluminum. Both of its faces are inscribed with the desired reference material.

Disc 32 has a central opening of diameter sufiicient to mount the disc rotatably on reduced shaft section 18, but insufficient to clear either sleeve 30 or enlarged shaft section 16. Thus the disc is retained between these two elements.

The front face ofdisc 32 may be inscribed with aplurality of concentric annular bands containing slide rule data and information. This is referenced by means of a pair of cursor arms 34, 36.

The bases of the cursor arms are provided with circular openings 38, 40, respectively and are marked longitudinally with central lines42, 44 which are used'toreference the data inscribed onthe front face of disc'32. They may be fabricated from any suitable material, preferably from clear plastic.

Cursor arms34, 36 are mounted in such a manner that they lie in frictional engagement with each other. The degree of friction is predetermined and controlled so that the friction between the cursors will always be greater than that between the cursors and the. adjacent elements, i.e., the bolt 20 on the one side and reference disc 32 on the other.

This result is brought about by mounting the arms on sleeve 30 described above. The sleeve then is journaled on reduced shaft segment 18 which freely rotates about the shaft.

The cursor arms are spaced slightly from the adjacent parts. This is accomplished by inserting them between thin washers 46, 48. These preferably are made of low friction plastic material such as Teflon. As a consequence of this spacing, and of the frictional engagement of the cursor arms with each other, and the regulated pressure applied by spring washer 28, both cursor arms will travel about the central shaft as a unit when a displacing force is placed against one of the arms only. However, if at the same time a restraining force is applied to the companion arm, the one cursor arm may be rotated about the shaft independently of the other.

As indicated, the backface of disc 32 may be marked with useful reference information. This is read and supplemented by mounting on the shaft one or more supplemental reference discs 50, 52. These have central openings which enable their mounting on the enlarged segment 16 of the shaft next to each other and next to the back face of disc 32.

Reference discs 50, 52 are made of a suitable material such as thin plastic which may be printed with the desired information. They are constructed and arranged in such a manner that a plurality of the discs, two in the illustration, may be used in conjunction with each other to record and make useful a wealth of technical information.

To this end the reference information on the backface of disc 32, as well as on the front faces of discs 50, 52 may be recorded in concentric annular bands, as shown in FIG. 2. These bands may be divided transversely into a plurality of wedge-shaped segments. Each disc 50, 52 then is provided with a corresponding wedge-shaped observation window 54, 56, respectively.

Reference discs 50, 52 are mounted for free rotation, with reference to each other and with reference also to disc 32. To this end they are spaced by means of washers 58 and 60 placed respectively between discs 32 and 50 and discs 50 and 52. The raised portion 14 of the inner face of nut 10 serves as a third washer, facilitating the ready adjustment of the discs, by means of integral finger tabs 62, 64.

This arrangement makes all of the information on the reference surfaces of all three discs readily observable. The information on' the outer surface of disc 52 is uncovered and accessible. By shifting discs 52 and 50 to various positions, the information on the face of disc 50'and underlying disc 52 may be observed through window 56 of the latter.

By adjusting discs 50, 52 so that windows 54, 56 register with each other and moving the two discs as a unit, the underlying information on the backface of disc 32 is made available.

The circular slide rule described above is adapted particularly for interconverting weight and atomic percentages of chemical elements, and for referencing pertinent information concerning the elements and other physical or chemical subject matter. 1

In this application the front face of disc 32 is marked with four annular concentric scales, differently colored to aid in identification. The outermost scale is a scale of the chemical elements. It is marked with the symbols for the elements in order of increasing atomic weight. v

The next scale inwardly is a conversion scale. It indicates weight or atomic percentage values.

The third scale is a log scale. It is in direct correspondence with the element scale.

The fourth or innermost scale is a conversion scale for converting temperature from degrees centigrade to degrees fahrenheit or vice versa.

The scales on the front face of disc 32 may be used for the rapid interconversion of weight and atomic percentages for any binary combination of chemical elements or compounds. The log scale may be used in solving problems in multiplication, division and proportion, in the manner of a conventional slide rule. The temperature conversion scale may be used to interconvert centigrade and fahrenheit temperatures.

In these operations the rule inherently is of great accuracy because in all but the temperature conversion scale, where it is not necessary, these scales may be arranged spirally to extend for a length of several feet. Two place accuracy beyond the decimal point is to be expected in most instances.

The scales on the face of disc 32 are read by adjusting cursors 34 and 36 with reference to the information on the disc surface. This may be done by holding the rule upright in one hand. The cursors then are rotated with the other hand. This is accomplished efficiently by positioning the short cursor first by rotating the long one. Because of the frictional interengagement between the two cursors, this is possible as long as one of the cursors is unrestrained.

The short cursor arm then is restrained with one thumb of one hand while the long cursor arm is positioned with the other hand. The desired positioning of the cursor and reading of the scales thus may be accomplished rapidly and accurate- The backface of disc 32 and the front faces of associated discs 50, 52 may be used to record information concerning the physical and chemical properties of the chemical elements.

As noted above, this information may be displayed in radial, wedge-shaped sections of the backface of disc 32 and the front face of disc 50. Disc 52 serves as a cover disc having indicia which make possible identifying the data on the other two discs. Such data may include information concerning the group, period, atomic number, atomic weight, crystal structure, melting point, boiling point, heat of fusion, etc., of the various chemical elements.

Where the element sought is on the face of disc 50, disc 52 may be rotated relative thereto until the corresponding information sector is aligned with an observation window 56 in disc 52. Where the information sought lies on the backface of disc 32, the observation windows in both of discs 50, 52 may be aligned with each other and the two discs moved as a unit until the desired information is uncovered.

Having thus described my invention in preferred embodiments, 1 claim as new and desire to protect by letters patent:

1. A circular slide rule comprising i Y a. a central shaft,

b. first, second and third reference discs mounted on the shaft coaxially with each other,

c. a pair of overlapped cursor arms rotatably mounted on the shaft, concentrically with the discs and overlying the outer face of the first disc in frictional engagement with each other,

. the shaft comprising a nut and a bolt,

e. the nut being formed with a central boss internally threaded to receive the bolt,

f. the peripheral surface of the boss being stepped to provide two segments of enlarged and restricted diameter respectively,

g. a sleeve rotatably mounted on the boss segment of restricted diameter and mounting the arms,

h. the boss segment of enlarged diameter mounting the second and third discs,

i. the first disc being mounted on the boss segment of restricted diameter between the sleeve and the boss segment of enlarged diameter, j. and at least one spring washer mounted on the shaft and arranged to exert lateral pressure against the discs.

2. The circular slide rule of claim 1 wherein the spring washer is mounted on the bolt between the head thereof and the first disc.

3. The slide rule of claim 1 including a spring washer mounted on the shaft of the bolt adjacent the head thereof and clamped in place by bearing action of the nut, a first plastic washer mounted on the shaft between the spring washer and the cursor arms, the cursor arms being in frictional engagement with each other, second, third and fourth washers interleaved between the discs, and a raised washerlike portion on the inner face of the nut and engaging the adjacent disc. 

1. A circular slide rule comprising a. a central shaft, b. first, second and third reference discs mounted on the shaft coaxially with each other, c. a pair of overlapped cursor arms rotatably mounted on the shaft, concentrically with the discs and overlying the outer face of the first disc in frictional engagement with each other, d. the shaft comprising a nut and a bolt, e. the nut being formed with a central boss internally threaded to receive the bolt, f. the peripheral surface of the boss being stepped to provide two segments of enlarged and restricted diameter respectively, g. a sleeve rotatably mounted on the boss segment of restricted diameter and mounting the arms, h. the boss segment of enlarged diameter mounting the second and third discs, i. the first disc being mounted on the boss segment of restricted diameter between the sleeve and the boss segment of enlarged diameter, j. and at least one spring washer mounted on the shaft and arranged to exert lateral pressure against the discs.
 2. The circular slide rule of claim 1 wherein the spring washer is mounted on the bolt between the head thereof and the first disc.
 3. The slide rule of claim 1 including a spring washer mounted on the shaft of the bolt adjacent the head thereof and clamped in place by bearing action of the nut, a first plastic washer mounted on the shaft between the spring washer and the cursor arms, the cursor arms being in frictional engagement with each other, second, third and fourth washers interleaved between the discs, and a raised washerlike portion on the inner face of the nut and engaging the adjacent disc. 